A comparison of the analgesic efficacy of local infiltration analgesia vs. intrathecal morphine after total knee replacement: A randomised controlled trial

BACKGROUNDLocal infiltration analgesia (LIA) is an effective pain management technique following total knee arthroplasty (TKA).OBJECTIVETo investigate if LIA provides better analgesia for patients undergoing unilateral TKA than intrathecal morphine.DESIGNRandomised controlled trial.SETTINGSingle tertiary referral centre.PATIENTSConsecutive American Society of Anesthesiologists Physical Status I to III patients scheduled to undergo unilateral TKA were randomised to two groups.INTERVENTIONThe control group received spinal anaesthesia with intrathecal bupivacaine and preservative-free morphine 0.3mg. The intervention group received opioid-free spinal anaesthesia with bupivacaine, followed by intra-operative infiltration of the knee with levobupivacaine 2mgkg^-1 and adrenaline 0.5mg diluted to a volume of 100ml with 0.9% saline. An intra-articular catheter was placed during surgery and used to give a bolus of 15ml of levobupivacaine 0.5% on the morning of the first postoperative day.MAIN OUTCOME MEASURESVisual analogue scale (VAS) scores for pain were assessed repeatedly for 48h postoperatively, at rest and on passive knee flexion to 30°. The primary outcome was VAS scores for pain at rest and on movement at 24 postoperative hours. Secondary outcomes were VAS scores at rest and on movement at 2, 6, 12 and 48 postoperative hours, opioid consumption, degree of active flexion of operative knee achieved in the first 48h and the incidence of opioid-related side effects.RESULTSForty three patients completed the study. Mean (± SD) VAS scores for pain at 24h were lower in the intervention group than the control group at rest; 16.43 (± 20.3) vs. 37.2 (± 33.6), (P=0.029). VAS scores for pain at 24h on movement were also lower in the intervention group vs. the control group; 39.1 (± 22.8) vs. 57.0 (± 30.9), (P=0.037). VAS scores were also lower on movement; 25.9 (± 16.8) vs. 40.5 (± 24.0), (P=0.028) at 48h.CONCLUSIONWe conclude that LIA conferred superior analgesia compared with intrathecal morphine 0.3mg at 24 and 48h following TKA.TRIAL REGISTRATIONClinicaltrials.gov identifier: NCT01312415.